Liquid break circuit interrupter



Feb. 16, 1954 c, VAN s c 2,669,628

LIQUID BREAK CIRCUIT INTERRUPTER Filed Jan. 5, 1950 4 Sheets-Sheet l lnsujmion WITNESSES: INVENTOR ATTORNE Roswell C.Van Sickle.

F 1954 R. c. VAN SICKLE 2,669,628

LIQUID BREAK CIRCUIT INTERRUPTER Filed Jan. 5, 1950 Sheets-Sheet 2 Fig.2.

l2!) Insulation WITNESSES: a .3 mvamog RosweH Ovanslckle.

t a 4 ,6 W J TTORN Feb. 16, 1954 R. c. VAN SlCKLE 2,669,628

LIQUID BREAK CIRCUIT INTERRUPTER Filed Jan. 5, 1950 4 Sheets-Sheet 3 Fig.4.

Insulation WITNESSES: INVENTOR RoswellCVonSickle.

Feb. 16, 1954 R. c. VAN SICKLE 2,669,628

LIQUID BREAK CIRCUIT INTERRUPTER Filed Jan. 5, 1950 4 Sheets-Sheet 4 WITNESSES:

INVENTOR Roswell C.Vc|nSick|e.

flaw' qwwm Patented Feb. 16, 1954 LIQUID BREAK CIRCUIT INTERRUPTER Roswell C. Van Sickle, Wilkinsburg, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 5, 1950, Serial No. 136,931

15 Claims.

This invention relates to circuit interrupters in general, and more particularly to arc-extinguishing structures for circuit interrupters of the liquid break type.

A general object of my invention is to provide an improved piston construction for rendering an arc-extinguishing device of the liquid break type more effective during the interruption of low currents, such as charging currents.

A more specific object is to provide an improved piston construction in which a pair of cooperating pistons are disposed on opposite sides of the arc passage, and to direct the liquid flow from the piston chambers in such a manner as to effectively cooperate with the normal functioning of the arc-extinguishing device. Such a. construction is particularly effective when utilized with an arc-extinguishing device of the type in which the established arc is drawn in a narrow slot disposed in fiber plates, some of which contain U-shaped iron plates which distort the magnetic field about the established arc and thereby cause its lateral movement.

Another object is to provide an improved piston construction, preferably of the twin acting type, in conjunction with an arc-extinguishing device of the type in which U-shaped magnetic plates are employed to effect lateral movement of the are within the slot, and to dispose suitable venting means therein which cooperates both with the magnetic action and also with the piston action to effectively bring about the interruption of low currents, such as charging currents.

A further object of my invention is to provide a device of the foregoing type in which the piston construction may be rendered inoperative due to the high pressure during high current interruption when the piston action is not required, and yet to have the arc-extinguishing device function as effectively during such high current interruption as if the piston means were not present.

Further objects and advantages will readily become apparent upon reading the following specification taken in conjunction with the drawings in which,

Figure 1 is a side elevational view, with the tank in vertical section, of an improved circuit interrupter embodying my invention, the contact structure being shown in the fully open circuit position;

Fig. 2 is an enlarged vertical sectional view taken on the line IIII of Fig. 4 of the righthand are extinguishing unit of Fig. 1, the contact structure being shown in the partly open circuit position;

Fig. 3 is a sectional view taken along the line III-III of Fig. 2 looking in the direction of the arrows;

Fig. 4 is an end elevational view, partially in vertical section, taken along the line IVIV of Fig. 3, of my improved arc-extinguishing unit;

Fig. 5 is a plan view in section taken along the line V--V of Fig. 1, looking in the direction of the arrows, and

Figs. 6-11 are plan views of some of the plates employed in my improved arc-extinguishing device.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral I designates a tank, having an interiorly disposed insulating liner 2, filled to the level 3 with a suitable arc-extinguishing liquid 4, in this instance circuit breaker oil.

Depending from the cover 5 of the tank I are two terminal bushings 6, 1, to the lower ends of which depend identical arc-extinguishing units or devices, generally designated by the reference character 8, The arc-extinguishing units 8 are electrically interconnected, in the closed circuit position, not shown, by a conducting bridging member 9 having upstanding movable contact portions III. In the closed circuit position the movable contacts ID are moved up interiorly within the units 8 by an insulating lift rod II. The lift rod or operating rod H is actuated by any suitable mechanism, which forms no part of my invention.

Referring to Figs. 2-4, which more clearly illustrate the internal construction of the arc-extinguishing units 8, it will be observed that the units 8 are constructed of a plurality of contiguously disposed insulating plates of the proper configuration, and are maintained in abutting engagement by a plurality of, in this instance four, tie rods l2. The steel bolts 12 have insulating sleeves l2a disposed thereabout with molded insulated heads I2b at their lower ends. The topmost insulating plate of the unit 8 is herein designated by the reference numeral E i, and is shown more clearly in Fig. 8. The fiber plate Hi has a pair of apertures E5 or other apertures H, the purpose for which will be more fully explained hereinafter. The plate Hi also has an enlarged sict it formed thereinv Immediately below the top plate M is an insulating flow plate, herein designated by the reference numeral i9, and shown more clearly by the full lines of Fig. 8. It will be observed that the flow plate i9 has apertures l5 formed therein which communicate by passage means 23, in this instance comprising a pair of inlet passages 2!, which lead from the apertures E5 to an enlarged cutout portion 22. The enlarged cutout portion 22 communicates with a narrow slot la. The flow" plate is also has the small apertures it formed" therein. The flow plate 19, as well as the top plate M, in addition has apertures 23' provided therein to accommodate the't'ie rods l2.

Immediately below the flow plate is is an insulating plate herein designated bythe-re'ference numeral 25 and shown more clearly in- Fig. 8. The plate 25 has the apertures i5, i6 and'fis, and in addition has an enlarged slot or orifice 26, which partially registers with the'enlarged'slo't i? of the plate It. The orifice 25, however, com municates with a narrow slot 2?" as more clearly shown in Fig. 8.

Immediately below the plate 25 is a vent plate 28 shown" more clearlyby the full lines of Fig. 9. The vent plate 23 has a slot 2% formed therein, which communicates by means of a narrow slot 39 to an enlarged'portion 3! which vents out of the unit 8 by means of a communicating vent passage 32'. The plate'28'a1so has the apertures HS and 23. It will also be observed that the plate 28 has provided therein" an irregular aperture I5a, which with the exception of the projections i522 is the same size as the aperture heretofore described and the purpose for which will appear more clearly hereinafter.

The next plate in the arc-extinguishing device 8 is a second vent plate herein designated by the referencenumeral- 3'4, and shownmore clearly by the dotted-lines in Fig. 9. It will be noted that the ventplate 3 is provided with a plurality of communicating pockets 35, which communicate by means of the vent passage 32-170 the region exteriorly of theunit ii.

The next plate in the unit 8 isherein designated by the reference numeral-35', and is shown more clearly by the full lines in Fig. 6 with the iron plate 3'! omitted. In other words, the plate 36 has the external outline as shown in full'lines in Fig. 6, but is provided with an enlarged slot 38, which communicates by means of a narrow slot 39 to anenlarged portion 56. The plate 35 is herein termed a guard plate, the reason forwhich will appear more clearlyhereinafter.

Thenext plate in the unit 8 is herein termed aliner insulatingplate d I, and is shown more clearly by the fulllines in Fig. 6. Theliner plate M has the enlarged slot 33 communicating with the narrow slot 39, which in turn communicates with the enlar ed portion The U-shaped iron plate d'i', previously mentioned, is of the same thickness as theliner plate 4! and is inserted therein, as shown more clearly in Fig. 6. It will be noted that the liner plate M protects the legs 4 f the U-shaped iron plate 3'1 from the are which is drawn within the arcing slot or passage 43. Immediately below the liner plate 4'! with itsiron plate 3? is a second guard'plate 36.

Then follows two insulating pocketanjd vent plates 44 more clearly shown in Fig. 7. The pocket and vent plate 44 has provided therein, as do the other plates, the apertures 23 to accommodate the tie rods l2, and in addition has a plurality of communicating pockets 45, which vent out of the unit 8 by means of a vent passage 46.

Then follows a group consisting of two guard plates 36 and a liner plate M with its inserted iron plate 31, two more pockets and vent plates 44, a third grouping of the guard plates 36 between which is disposed a liner plate 4| and its inserted iron plate 31. I

Then follows two pocketpla'tesfMhaving the same configuration as the pocket and vent plate 54 with the exception that the vent passage 46 is omitted by the integrally formed portion 48. Then follows" another grouping of two guard plates 36 with an interposed liner 4| with its iron plate31, which' grouping is followed by two more platesfii" previously described. Then follows a vented guardplate t9 which has the same configuration as the guard plate 38 previously described but the enlarged slot 33 communicates with the region exteriorly of the unit 8 by means of a vent passage 50, which is formed by elongating the-passage 38'- by the dotted-lines 5'4 of Fig. 6. Then follows a vented liner plate 52; which has the' same configuration asthe'liner plate-4:1: with the exception that the enlarged slot 38' communicates by means-of a vent-passage 50 130 the region outside of the unit-. 8". Then follows' a second vented guard plate 49.

Then follows two ventand pocket platesiEB more clearly shown i'nFig. 10. E ach' vent andpocket plate 53 has four pockets 45}-which-communicate with a vent passagefi'to the region'ex teriorly of the unit. Then follows asecond grouping of two vented guard plates 49 wi'tH- an interposed vented liner plate 52 with its iron plate 37. Then follows two more-vent and pocket plates 53. Thenfollows' a side vented plate 56 having a configuration more clearly shown in Fig; 11. Theplate Whas' the apertures 23and'ha's'an open slot 5'? formed therein. The next two plates 58- and' 59 have essentially the open slots 5-?- formed 4 therein.

When the several plates are stacked'upon the tie rods l2 and'thereby disposed in contiguous'relation, the slots 26, S8 align to form the'arcing passage or slot 43 within which the arc'fitf'is drawn. The are 60' naturally hasa magnetic field surrounding it which is distorted by the presence of the iron plates 31. The result of the distorted magnetic field is to draw the are from the arcing passage 53 through the several narrow slots 2?, 3t, 39 to the enlarged portions where the arc is positioned in a turbulent region' in which it is bombarded by gas and unionized liquid particles resulting. from the action of the are 60 upon the oil disposed in the pockets Furthermore the venting passages 48 provided in the vent plates at permit the unionized gas and liquid particles to pass out of the unit'8 transverselyof the arc stream to effect its extinction. The greater the current magnitude passing through the are 6% the more the are 60 will be forcibly drawn to the right, as viewed in Fig. 2, toward the vents 36 where it will be bombarded more intensely as a result of'the increased pressure formed thereat.

The stationary contact structure 61 will'now be described. The stationary contact structure 6! includes an adapter 62 which'isscrewed' o'nto the lower ends of the terminal studs- 63 passing interiorly through thebushings: 6, T and: is

clamped thereto by nuts and bolts not shown. The adapter 62 is secured by bolts 64 (Fig. 1) to the stationary contact housing 65 which in this instance comprises a casting 86. The casting 66 encloses a pair of stationary contacts 61 which grip the upper ends of the sides of the movable contact 18. The inward biasing action is exerted by contact springs 88 surrounding studs 89 fixed to and movable with the contacts 81. The studs 69 extend through slots formed in the side walls of the casting 35 so that they are free to move.

The tie rods [2 of the unit 8 pass through apertures formed in side lugs 12 (Fig. 1) integrally formed with the side walls of the casting 66. The contacts 6? are mounted on a pair of pins 13, the latter being journalled within the end walls of the casting 66. The contacts 6'! are connected by a flexible shunt '14, which is secured to the adapter 62 by means of a bolt '15.

I provide an arc horn is extending within the upper slot ll of the top plate 14, to which the upper terminal end of the are 88 may attach. To facilitate the interuption of low currents, such as charging currents, which form little pressure within the arcing passage 43 of the unit 8, and which are also acted upon laterally with little magnetic force, I provide a piston means, generally designated by the reference numeral 18, and comprising a twin pair of coacting pistons 19 (Fig. 4) on opposite sides of the arc passage 43 and movable within piston chambers 88.

Preferably, the piston cylinders 88 have apertures 8| provided at their upper ends to freely vent the region 82 in back of the pistons 19. A pair of piston springs 83 (Fig. 4) are disposed within the piston cylinders 88 and serve to bias the pistons 79 downwardly in a working direction to force liquid, in this instance oil, through the inlet passages 2| and into the arc passage 43.

The lower end of the piston cylinder 80 is secured as by welding or brazing to a metallic apertured plate 84 which has three apertures I6 provided therethrough. Three bolts 85 pass through the several apertures 16 provided in the plate 84 and also through the apertures 16 of the upper five insulating plates of the unit 8. A second metallic plate 83 is provided with three such apertures is formed therein. The bolts 85 also pass through the plate 86, and nuts 8'! are employed to secure the two clamping plates 84, 86 rigidly in place on opposite sides of the upper five plates of the unit 8. The pistons ill have a lower extending insulating portion 88, which is picked up during the closing stroke by bumpers 89 secured by brackets 98 to the bridging member 9.

Preferably during such a closing stroke, oil is admitted to the region 9! below the pistons 79 past a valve 92a, which rests upon the plate 86, and also through the passages 2 l. Consequently, during such a closing operation, when the bumpers 89 have picked up the piston extensions or rods 88, the valve 92a will be lifted by suction to permit oil outside of the unit 8 to pass through the aperture 92 of the plate 83 and into the region 9|. As mentioned, oil will also be drawn through the passages 2|.

In the closed circuit position of the interrupter, the lift rod I i has moved the contacts m upwardly into engagement with the stationary contacts 61, and the bumpers 89 have moved the pistons 9 to their upward charged position with the springs 83 compressed. During the opening operation, when the lift rod I l moves down carrying with it the contacts l0 and the bumpers 89, if the pressure is relatively low within the unit 8, as caused by the interruption of low currents, such as charging currents, the springs 83 will overcome the pressure existing within the arc passage 43 and will force the pistons 19 downwardly, keeping the valve sleeve 92a closed and forcing oil through the inlet passages 2! on both sides of the arc passage 43 and toward the are 68. This oil will be forced through the orifice restriction 26 of plate 25 and transversely of the are 60 out through the vents 32, 46 provided in the plates 28, 34 and 44, and also downwardly within the arcing passage 43 to the vent 93 disposed at the lower end of the unit 8.

The entrance of such fresh oil into the arc passage 43 under pressure, as caused by the springs 83, will quickly extinguish any such low current arc.

, From the foregoing description of my improved interrupter, it will be apparent that I have provided an improved piston construction in which a pair of cooperating twin pistons 79 are disposed on opposite sides of the arcing passage 43 and serve to intensify the oil action upon the are 68 during low current interruption, when the pressure normally generated by the arc is relatively low.

During the interruption of high currents, the increased pressure, consequently formed, may stall, or even back up the pistons 19 so that they are rendered inoperative. It will be noticed that each piston 59 has a stop 59a which, upon engagement with the plate lei), prevents further upward movement of the piston 19. Subsequently, upon a subsidence of the pressure within the arcin passage following extinction of the are 68, the pistons ill will only then be eifective to force a flushing flow of oil through the inlet passages 2| and into the arc passage 43 to wash contaminated oil through the vent passages 32, 45 and also out the lower vent 93 of the unit 3.

The operation of the piston means 18 coopcrates in the afor described novel manner with the magnetic action exerted by the magnetic plates 3'! upon the are 88. In other words, the oil under pressure entering through the inlet passages 2i and through the orifice 23 assists the magnetic biasing force exerted by the plates 31 to move the are 58 back through the narrow slots 27, 39 and toward the enlarged portions 48 adjacent the vents 32, M, in which position the arc is subjected to an intense transverse oil blast produced not only by the decomposition of the oil within the pockets 35, 45, but also by the oil blast emerging from the inlet passages 25. The combination of such oil blasts is effective to quickly cause the extinction of the are 88 during low current interruption, when the normal magnetic action exerted upon the arc Bil by the plates 31 is relatively weak.

It will moreover be noted that the incorporation of the piston means '58 in no manner has an injurious effect upon the normal functioning of the magnetic extinguisher 8 during the interruption of relatively high currents. In such a case, the pistons l9 are merely stalled by the high pressure in their upper position, and the normal magnetic extinguishing action is carried on within the unit 8. In such case, the pistons l9 are subsequently eiiective to produce the flushing fiow of oil, as previously described.

7 Although I have shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration,

1:- andthatchanges and modificationsmay readily be made therein by those skilled in: the .art,'With:-.' oultfdeparting from the spirit andnscopje .of the appended claims.

lclaim as my invention:

1-. A circuitinterrupter of the liquid break type includin means at leastpartly ofinsulatingma: terial defining-an elongated arcing slot, contact meansfor establishing an arc alongsaid slot, ventingineans disposed along one sideof the arcing slot, magnetic means for biasingthearc laterally within the arcing slot toward said vents ing means, piston means movable during. the opening operation independently of the contact means for forcing liquid into the arcing slot ads jacent one end thereof and towardsaid venting means, and the piston means forcing liquid to flow longitudinally along the slot in. the direction of arc lengthening at the point Where the are. is initially established.

A circuit interrupter of the liquid break type including means at least partly of insulating material d efining an elongated arcing slot, contact means for establishing an are along said slot, venting means disposed along one side of the arcing slot, magnetic means for biasing the arc laterally Within the arcing slot toward said venting means, piston means including a pair of pistons disposed on opposite sides of the arcing slot movable during the opening operation independently of the contact means for forcing liquid into the arcing slot adjacent one end thereof and toward said venting means, and the piston means forcing liquid to flow longitudinally along the slot in the direction of arc lengthening at the point Where the arc is initially established.

3. A circuit interrupter of the liquid break type including means at least partly of insulating material defining an elongated arcing slot, contact means for establishing an arc along said slot, venting means disposed adjacent one end of the rcing slot, magnetic means for biasing the arc laterally within the arcing slot toward said venting means, piston means movable during the opening. operation independently of the contact means for forcing liquid into the arcing slot adjacent one end thereof and toward said venting means, and the piston means forcing liquid to not: longitudinally along the slot in the direction of arc lengthening at the point W ere the are is initially established.

4. A circuit interrupter of the liquid break type including means at least partly of insulating material defining an elongated arcing slot, contact means for establishing an are along said slot, venting means disposed adjacent one end of the arcing slot, magnetic means fOlflbiEiSiIlgthC-B arc laterally within the arcing slot toward said venting means, piston means including a pair of pistons disposed on opposite sides of the arcing slot movable during the opening operation independently of the contact means for forcing liquid into the arcing slot adjacent one end thereof and toward said venting means, and the piston means forcing liquid to flow longitudinally along the slot in the direction of arc lengthening at the point Where the arc is initially established.

' 5. A circuit interrupter of the liquid break type including 11162111534 3 least partly of insulating material defining an elongated arcing slot, contact means for establishing an arc along said slot, venting means disposed along one side of the arc-.- in,, slot and adjacent one end thereof, magnetic ineans ior. biasing the arc laterally withinthe s ides le o r Said nture mans-pain means, for. biasing the arc laterally, withinthe arcing s'lotltoward said venting means, piston means including a pair of pistons disposed on, oppositesides of the arcing slot movable during, thjcopening operationindependently of thecon tact means for forcing liquid into the arcingslot. adjacent one end thereof and toward said vent ing, means, and the'piston means forcing liquid to flow longitudinally along the slot in th'efdii rection of arc lengtheningat the point wherelthel arc is initially established. I

7. A'circuit interrupter of the liquid breaktype. including an arc-extinguishing unit immersed. Within an arc-extinguishing liquid, the. unit comI-I, prising a plurality of insulatingplates disposed in contiguous relationship, certain of said plates having slots provided therein to form upon alignment an elongatedarcing passage, a stationary contact disposed adjacent one end of-the arcing passage, a movable contact movable along said arcing passage out of engagement from the stationary contact to establish an arc therebetwe'e'n along said arcingpassage, one or more of the end plates adjacent said end of the arcing passage having. ortions projecting laterally beyond the rest of the, plates, a pair of piston cylinders dis: posed at the projecting portions of the said one or more plates on opposite, sides of the arcing passage, alpair of pistons movable Within said piston cylinde'rs independently of the'contacts; means biasing, said pistons to move withinsaid piston cylinders in a direction towardlthe other end of thearcing passage, one of said projecting end plates having a pair of communicatinginlet passages communicating from the piston cylin ders to the arcing passage on opposite sides thereof, and means movable with the movable contact and separable from the pistons for charging the latter during the closing operation.

8.- A circuit interrupter of the liquid break type including an arc-extinguishing unit immersed within an arc-extinguishing liquid, the unitcomi prising a pluralityof insulating plates disposed in contiguous relationship, certain of said plates having. slots provided therein to form uponalign: merit an elongated arcing passage, av stationary contact disposed adjacent one end of the arcing passage, a movable contact movable along. said arcing passage out of engagement from the sta tionarycontact to establish an arc therebet'ween alon said arcing passage, one or more of the end plates adjacent said end of the arcing "p assage having portions projecting laterally beyond the rest of the plates, 2. pair of piston cylinders disposed at theprojecting portions of the said one or morepl s 011 PP i e des of the, arc: in passage, a pair of pistons movablewithin saidpiston cylinders, independently of the con tacts, means biasing said pistons ,to movewith; in aid piston cylinders in .a direction toward the one, en ape-sesame' s mama jecting end plates having at least an inlet passage leading from one of said piston cylinders to the arcing passage, and means movable with the movable contact and separable from the pistons for charging the latter during the closing operation.

9. A circuit interrupter of the liquid break type including an arc-extinguishing unit immersed within an arc-extinguishing liquid, the unit comprising a plurality of insulating plates disposed in contiguous relationship, certain of said plates having slots provided therein to form upon alignment an elongated arcing passage, a stationary contact disposed adjacent one end of the arcing passage, a movable contact movable along aid arcing passage out of engagement from the stationary contact to establish an arc therebetween along said arcing passage, one or more of the end plates adjacent said end of the arcing passage having portions projecting laterally beyond the rest of the plates, a pair of piston cylinders disposed at the projecting portions of the said one or more plates on opposite sides of the arcing passage, a pair of pistons movable within said piston cylinders independently of the contacts, means biasing said pistons to move within said piston cylinders in a direction toward the other end of the arcing passage, one or more of the projecting end plates having inlet passages communicating from the piston cylinders to the arcing passage, and means movable with the movable contact and separable from the pistons for charging the latter during the closing operation.

10. A circuit interrupter of the liquid break type including an arc-extinguishing unit immersed within an arc-extinguishing liquid, the unit comprising a plurality of insulating plates disposed in contiguous relationship, certain of said plates having slots provided therein to form upon alignment an elongated arcing passage, a stationary contact disposed adjacent one end of the arcing passage, a movable contact movable along said arcing passage out of engagement from the stationary contact to establish an arc therebetween along said arcing passage, one or more of the end plates adjacent said end of the arcing passage having portions projecting laterally beyond the rest of the plates, a pair of piston cylinders disposed at the projecting portions of the said one or more plates on opposite sides of the arcing passage, a pair of pistons movable within said piston cylinder independently of the contacts, means biasing said pistons to move within said piston cylinders in a direction toward the other end of the arcing passage, one of said projecting end plates having a pair of communicating inlet passages communicating from the piston cylinders to the arcing passage on opposite sides thereof, the pistons having extensions, the movable contact carrying a pair of bumpers, and the bumpers charging the pistons during the closing operation of the interrupter.

11. A circuit interrupter of the liquid break type including an arc-extinguishing unit immersed within an arc-extinguishing liquid, the unit comprising a plurality of insulating plates disposed in a contiguous relationship, certain of said plates having slots provided therein to form upon alignment an elongated arcing passage, a stationary contact disposed adjacent one end of the arcing passage, a movable contact movable along said arcing passage out of engagement from the stationary contact to establish an arc therebetween along said arcing passage, one or more of the end plates adjacent said end of the arcing passage having portions projecting laterally beyond the rest of the plates, a pair of piston cylinders disposed at the projecting portions of the said one or more plates on opposite sides or the arcing passage, a pair of pistons movable within said piston cylinders independently of the contacts, means biasing said pistons to move Within said piston cylinders in a direction toward the other end of the arcing passage, one of said projecting end plates having a pair of communicating inlet passages communicating from the piston cylinders to the arcing passage on opposite sides thereof, and a valve disposed adjacent the working end of each piston cylinder.

12. A circuit interrupter of the liquid break type including an arc-extinguishing unit immersed within an arc-extinguishing liquid, the unit comprising a plurality of insulating plates disposed in contiguous relationship, certain of said plates having slots provided therein to form upon alignment an elongated arcing passage, a stationary contact disposed adjacent one end of the arcing passage, a movable contact movable along said arcing passage out of en agement from the stationary contact to establish an arc therebetween along said arcing passage, one or more of the end plates adjacent said end of the arcing passage having portions projecting laterally beyond the rest of the plates, a pair of piston cylinders disposed at the projecting portions of the said one or more plates on opposite sides of the arcing passage, a pair of pistons movable Within said piston cylinder independently of the contacts, means biasing said pistons to move within said piston cylinders in a direction toward the other end of the arcing passage, one of said projecting end plates having a pair of communicating inlet passages communicating from the piston cylinders to the arcing passage on opposite sides thereof, the pistons having extensions, the movable contact carrying a pair of bumpers, the bumpers charging the pistons during the closing operation of the interrupter, and a valve disposed adjacent the Working end of each piston cylinder.

13. A circuit interrupter of the liquid break type including means at least partly of insulating material defining an elongated arcing slot, contact means for establishing an are along said arcing slot, an orifice restriction through which the arc is initially drawn disposed at one place along said slot, venting means for the arcing slot disposed axially on one side of the orifice restriction, piston means for forcing liquid into the arcing slot disposed axially on the other side of the orifice restriction, and magnetic means for biasing the arc laterally within the arcing slot.

14. A circuit interrupter of the liquid break type including means at least partly of insulating material defining an elongated arcing slot, contact means for establishing an are along said arcing slot, an orifice restriction through which the arc is initially drawn disposed at one place along said slot, venting means for the arcing slot disposed axially on one side of the orifice restriction, piston means for forcing liquid into the arcing slot disposed axially on the other side or the orifice restriction, and magnetic means for biasing the arc laterally within the arcing slot toward said venting means.

15. A circuit interrupter of the liquid break type including means at least partly of insulating material defining an elongated arcing slot, contact means for establishing an are along said arcing" 'sidt,fah t afifie thrdfigh the arc is initially drawn disppsed at one'place -orificerrestriction, and the are moving laterally within the arcing slot on said one side of the orifice restriction and becoming extinguished.

"ao'swm" 'VA'N' SICKLE.

"Rereins "Cite in the iilegf fithist bat'fi't UNITED STATES PATENTS Number Number "Nadine ll at e Leeds Ju1y"2,*1 0%6 Peters Dec. 3,1946 'Leedset a1 July 2939 13 Baker et'al. 'Feb."'22,f19 4;9 Bartlett "Augf 5, I952 FOREIGN PATENTS Country l Date 

